A distribution of values is normal with a mean of 36.2 and a standard deviation of 51.7. Find P89

Answer 1

Hi Kala,

P89 means 89th percentile and you know data are normally distributed, so check the interior of the z-score table for 89% or 0.89. The closest value on my z-table is 0.8907 at z=1.23. Now you know z, so you can use the classic equation in elementary statistics:

z= (x-mu)/sigma

z=1.23

x=x, the value we are interested in

mu=mean=36.2

sigma=standard deviation=51.7

1.23 = (x - 36.2)/51.7

Solve this for x, and you will have P89. I hope this helps.